Locking device

ABSTRACT

A locking device suitable for use in a gun to prevent unauthorized use of the gun includes a key operated lock (3) operable to expand a ring (8) into locking engagement with the gun chamber. In order to prevent removal of the device by applying force to the muzzle end of the device locking pins (14) are mounted in radial bores (11) to be driven radially outwardly by a tapered piston (18) if the piston is driven away from the muzzle end. An explosvie cartridge (23) is detonated by a firing pin (25) if force is applied to an end plate (26) thereby driving the piston in the desired manner.

This invention relates to a locking device which, upon actuation, islocked to a hollow body within which the device is situated. Although ofgeneral applicability the preferred embodiment of locking device isparticularly suitable for forming part of a safety device for firearms,the safety device being adapted to be secured by a key within thechamber of a firearm and to be locked permanently to the chamber of thefirearm upon actuation of the locking device of the invention.

According to one aspect of the present invention there is provided alocking device which, upon actuation, is locked to a hollow body withinwhich the device is situated, the locking device comprising: a bodyhaving a central longitudinal bore and a plurality of radial passagesextending from the bore radially outwardly to the surface of the body; alocking pin located in each passage with the radially inner end of eachpin located extending into the bore; an actuating member located in thebore, the actuating member having a cylindrical region and a taperingregion which tapers inwardly from the cylindrical region and beingpositioned such that upon axial movement of the actuating member thelocking pins will be cammed radially outwardly by the tapering regionand thereafter locked in a radial outward position by the cylindricalregion; a piston mounted in the cylinder and coupled to the actuatingmember for axially moving the actuating member; an explosive charge fordriving the piston; and means for detonating the explosive charge inresponse to application of axial force to one end of the device.

A security device, particularly suitable for shot guns, has beenproposed which has the overall size and configuration of a shot guncartridge, but which incorporates a lock which enables the device to belocked into the chamber of a shot gun. One such device of this typeincorporates a ring which is cammed radially outwardly by a taper tolock the security device into engagement with the wall of the chamber.Such devices suffer, however, from the disadvantage that they can oftenbe forced from the chamber by inserting a suitable drift through thebarrel from the muzzle end to apply an axial force to the securitydevice.

If a locking device in accordance with the present invention isincorporated within the security device any attempt to remove thesecurity device in this manner will result in detonation of theexplosive charge with the result that the locking pins will be drivenradially outwardly into locking engagement with the walls of thechamber. Once this has occurred extreme force will be necessary to drivethe security device from the chamber, and the application of such forcewill result in substantial damage to the chambers of the gun.

Whilst the invention is particularly suited to use in a security devicefor a firearm it will be appreciated that it is of more generalapplicability and may be used to provide a plug which may be installedextremely rapidly within a hollow body to provide a permanent closure tothe hole in which the device is located.

The invention will be better understood from the following descriptionof a preferred embodiment thereof, given by way of example only,reference being had to the accompanying drawing wherein the singleFigure illustrates schematically in partial axial cross-section apreferred embodiment of the invention.

Referring to the drawing there is illustrated an embodiment of lockingdevice 1 according to the present invention which forms part of asecurity device 2 for a shot gun. The overall configuration of thesecurity device 2 is similar to that of a conventional shot guncartridge so that the entire security device may be positioned withinthe chamber of a shot gun. Once the security device has been sopositioned a key operated lock 3 (which is only shown in outline in thedrawing) is actuated to rotate a screw threaded member 4 which draws thelock housing 5 towards the body 6 of the locking device. An end region 7of the body 6 is formed with a taper on which is mounted a split ring 8having a matching taper. Movement of the lock housing 5 towards the body6 will accordingly force the ring 8 up the taper 7 to expand the ringradially into locking engagement with the wall of the chamber of thegun. Once the ring 8 has been expanded into firm contact with thechamber wall the key is removed from the lock 3 and the shot gun issecure.

The locking device 1 prevents any attempt to drive the security device 2from the chamber of the gun by applying a force to the end 9 of thesecurity device using a drift which is inserted through the muzzle endof the barrel of the gun.

The locking device 1 comprises the body 6 which is machined from asuitable material, for example mild steel. The body 6 includes an axialbore 10 and a plurality of radially extending passages 11 which extendfrom the bore 10 to the radially outer surface 12 of the body 6. In atypical embodiment of the invention six radially extending passages 11are provided equi-angularly spaced about the axis 13 of the lockingdevice. In each passage 11 a locking pin 14 is provided. Only one suchlocking pin 14 is illustrated in the drawing in the interests ofclarity. The locking pins 14 may be of any suitable material, forexample hardened steel, and each has a pointed radially outer end 15 anda rounded radially inner end 16. The radially inner ends 16 project intothe bore 10 and the radially outer ends 15 are substantially flush withthe radially outer surface 12 of the body 6. If desired, means in theform of a hoop extending about the body 12 may be provided to preventaccidental dislodgement of the pins 14. The hoop may be of any suitablematerial, for example a thin copper alloy or of plastics.

The radially inner ends 16 of the pins 14 rest on a first cylindricalregion 17 of an actuating member 18. The actuating member 18 includes asecond cylindrical region 19 and a third cylindrical region 20 both ofwhich are a snug fit within the cylindrical bore 10. The cylindricalregion 17 is connected to the cylindrical region 19 by a tapering region21. Upon movement of the actuating member 18 to the right as viewed inthe drawing the pins 14 will be cammed radially outwardly by contact ofthe radially inner ends 16 with the tapering region 21 with the resultthat the radially outer ends 15 of the pins will be driven into lockingengagement with the wall of the chamber of the gun. The amount of axialmovement available to the actuating member is sufficient for theactuating member to be driven to a position in which the radially innerends 16 of the locking pins rest against the cylindrical region 19 ofthe actuating member. Accordingly, once the actuating member has arrivedat this position it cannot be cammed in the reverse direction by theradially inward force which is applied to the pins 14 by virtue of theirengagement with the chamber wall.

A piston 22 is formed integrally with the actuating member 18 andoperates in the cylindrical bore 20. In order to drive the piston, andwith it the actuating member, an explosive charge is provided by meansof a blank cartridge 23 which is positioned within an end region of thebore 10 and is held in position by means of a cap 24 which screwthreadingly engages the exterior surface of the body 6. The piston 22 issized to be tight fit within the bore 10 so that upon detonation of thecartridge 23 there is minimum passage of gasses past the piston. Theentire explosive force of the cartridge is accordingly contained betweenthe piston 22 and the cartridge case and the piston is driven to theright as viewed in the drawing with sufficient force to move theactuating member to the right to set the locking device as describedabove.

Detonation of the cartridge 23 is achieved by means of a firing pin 25which abuts an end plate 26. A pair of Belleville washers 27 are locatedbetween the plate 26 and the cap 24 so that upon application of asteadily increased force to the exposed end of the plate 26 there willbe little movement of the plate 26 until the force of the Bellevillewashers 27 is overcome, whereupon the plate 26 will snap to the right asviewed in the drawing applying a percussive force to the firing pin 25to detonate the cartridge.

Preferably, a plastics protective sleeve is positioned over the cap 24and the plate 26 in order to ensure that if the security device isdropped on the floor or otherwise accidentally knocked the cartridgewill not be detonated. It will be noted, however, that in the event ofaccidental detonation of the cartridge there is no risk that the pins 15will be propelled out of their associated bores because there is minimalflow of gas past the piston 22 and accordingly after the pins havereached the top of the tapered region 21 there will be no further forceavailable to drive them from the body. The retaining hoop over the pinswill absorb any kinetic energy posed by the pins at this point.

Whilst the invention has been described with particular reference to asecurity device for a gun it will be appreciated that the locking deviceof the present invention if of general applicability and may be used forany purpose where a rapid, reliable, and permanent closure of a hole isrequired.

We claim:
 1. A locking device which, upon actuation, is locked to ahollow body within which the device is situated, the locking devicecomprising: a body having a central longitudinal bore and a plurality ofradial passages extending from the bore radially outwardly to thesurface of the body; a locking pin located in each passage with theradially inner end of each pin located extending into the bore; anactuating member located in the bore, the actuating member having acylindrical region and a tapering region which tapers inwardly from thecylindrical region and being positioned such that upon axial movement ofthe actuating member the locking pins will be cammed radially outwardlyby the tapering region and thereafter locked in a radial outwardposition by the cylindrical region; a piston mounted in a cylinder andcoupled to the actuating member for axially moving the actuating member;an explosive charge for driving the piston; and means for detonating theexplosive charge in response to application of axial force to one end ofthe device.
 2. A locking device according to claim 1 incorporating meansallowing the locking device to be releasably secured in the hollow body.3. A locking device according to claim 2 wherein said means allowing thelocking device to be releasably secured in the hollow body comprises akey operated means for radially expanding the locking device intoengagement with the hollow body.
 4. A locking device according to claim1 wherein the radially outer end of each pin is pointed.
 5. A lockingdevice according to claim 1, wherein a hoop of suitable material isprovided about the body of the locking device for preventing accidentaldislodgement of the pins.
 6. A locking device according to claim 1,wherein the cylinder in which the piston is mounted is part of thelongitudinal bore of the body.
 7. A locking device according to claim 1,wherein the means for detonating the explosive charge comprises a firingpin and means for resisting movement of the firing pin towards theexplosive charge until a force in excess of a predetermined level isapplied to the device.
 8. A locking device according to claim 7 whereinat least one Belleville washer resists movement of the firing pintowards the explosive charge until a force in excess of thepredetermined level is applied to the device whereupon the Bellevillewasher snaps to an inverted form thereby allowing the firing pin toapply a percussive force to the explosive charge.